Cigarette smokers are increasingly engaging in use of alternative tobacco products: cigars, waterpipe tobacco, and smokeless tobacco (SLT). This emerging trend in tobacco consumption may reflect smokers' beliefs that these products are less lethal than cigarettes. In particular, novel SLT products (e.g., snus) may be used by smokers for purposes of reducing smoking-related harms and/or ceasing cigarettes altogether. Smokers able to successfully replace their cigarettes with these products may incur such health-related benefits. Public health officials are concerned, however, that smokers may instead supplement their cigarette use, especially given industry marketing practices coupled with indoor smoking restrictions. For instance, novel SLT products have been promoted by the industry for smokers to use in situations where cigarettes are prohibited. Similarly, some smokers report use of traditional SLT products (e.g., moist snuff) for this same reason. To better understand how smokers' health risks are affected as a result of concomitant SLT use, their natural patterns of use need to be characterized. In the proposed study, dual cigarette-SLT users will use an electronic diary for 14 consecutive days in their own environment. They will record each cigarette and SLT use episode as it occurs, as well as related contextual details (e.g., location/activity of use) and ratings of mood and craving. At the end of each day, participants will provide a saliva sample for later analysis of cotinine (metabolite of nicotine). The goals of this study are to determine whether a) cigarette smoking and salivary cotinine levels differ between dual versus single use days, and b) SLT use is promoted among smokers by temporal and contextual (e.g., indoor versus outdoor locations) factors. Study results will shed light on whether cigarette smokers' use of SLT is consistent with product supplementation or replacement, and thus whether this behavior influences their exposure to tobacco toxicants.